The U.S. stopped flying combat sorties over Libya on April 4th. NATO allies asked for the U.S. to keep flying combat missions for another 48 hours, and this kept American aircraft flying over the weekend. Until recently, American aircraft have flown about sixty percent of the sorties, but only about half of the combat sorties. About 55 percent of the sorties are for support (reconnaissance, electronic eavesdropping, aerial refueling). American aircraft will continue flying these, because in many cases, only the U.S. has the specialized aircraft for certain kinds of work.
The no-fly force has been averaging 100-200 sorties a day, but demonstrated the ability to fly as many as 300 a day when such a surge is needed. Over a thousand missiles and smart bombs have been used so far, in addition to about 150 cruise missiles. Operations began on March 19, when French aircraft flew several of its aircraft over Libya. On March 31st, NATO took over the operation. Plenty of aircraft were contributed, with most flying no more than one sortie a day.
NATO is trying to set up ground controllers among the rebels, to make it possible to call in smart bomb missions in urban areas. No one wants to send their own FAC (Forward Air Controller) teams in, but that may have already happened in a few cases.
The Kadaffi forces have learned to stay off the highways with military vehicles, and strive to appear as civilians (in trucks and cars) when moving about on the roads. This means the Kaddafi forces have less firepower inside the urban areas, but they also don't have to worry (at least not a lot) about getting hit by smart bombs or missiles.
But if NATO can get some kind of trained people on the ground, with radios that can talk to the warplane pilots above, Kaddafi's troops would be in big trouble.